Circadian rhythms in voluntary wheel-running activity in mammals are tightly coupled to the molecular oscillations of a master clock in the brain. As such, these daily rhythms in behavior can be used to study the influence of genetic, pharmacological, and environmental factors on the functioning of this circadian clock.
Verwey, M., Robinson, B., Amir, S. Recording and Analysis of Circadian Rhythms in Running-wheel Activity in Rodents. J. Vis. Exp. (71), e50186, doi:10.3791/50186 (2013).